Polylactic acid (PLA) and montmorillonite (CB) as filler were studied as coatings for cellulose based packages. Amorphous (AM) and semi crystalline (SC) PLA were used at different concentrations according to a 2 × 6 × 3 full factorial experimental design. CB loading was three concentrations and coating was performed by casting. Contact angle (CA), water vapor (WVP) and grease permeabilities were measured for each resultant package and were compared to commercial materials (Glassine Paper, Grease Proof Papers 1 and 2 produced commercially). Significant differences were found and the main factors were the type and concentration of PLA. The best values were: for grease penetration, +1800 s; WVP from 161.36 to 237.8 g·µm·kPa and CA from 69° to 73° for PLA-AM 0.5% and CB variable. These parameters are comparable to commercial packages used in the food industry. DSC revealed three different thermal events for PLA-SC and just T g for PLA-AM. Crystallinity was also verified, obtaining a ΔH crys of 3.7 J·g

High-resistance paper was manufactured by laccase-grafting of carboxymethyl cellulose (CMC) and chitosan (CPX) on Kraft pulp fiber. The reaction was mediated in the presence of laccase by one of the following polyphenols in the presence of air: gallic acid (GA), vanillic acid (VA) and catechol (1,2-DHB). Enzyme was added at constant loading (24 kg ton −1 ), 1% pulp consistency, 0.005% CMC, pH = 6.3 ± 0.5 and 2 mM of mediator. CPX content was assessed at two levels (0% and 0.005%). Treated pulps were analyzed by different mechanical tests (ring crush, mullen, corrugating medium test (CMT) flat crush of corrugating medium test and tension). An improvement in these parameters was obtained by biopolymer coupling and selected mediator. When using GA, three parameters increased more than 40%, while ring crush increased 120%. For the case of VA, properties were enhanced from 74% to 88% when CPX was added. For 1,2-DHB, there was not found a statistically significant difference between the results in the presence of CPX. Scanning electron microscopy, confocal microscopy, FTIR and 13 C NMR were used in all papers in order to evaluate grafting. Hence, it was possible to correlate polymerization with an improvement of paper's mechanical properties.

Paper recycling has increased in recent years. A principal consequence of this process is the problem of addressing some polymeric components known as stickies. A deep characterization of stickies sampled over one year in a recycled paper industry in México was performed. Based on their chemical structure, an enzymatic assay was performed using lipases. Compounds found in stickies by Fourier-transform infrared spectrometry were poly (butyl-acrylate), dioctyl phthalate, poly (vinyl-acetate), and poly (vinyl-acrylate). Pulp with 4% (w/w) consistency and pH = 6.2 was sampled directly from the mill once macrostickies were removed. Stickies were quantified by counting the tacky macrostructures in the liquid fraction of the pulp using a Neubauer chamber before the paper was made, and they were analyzed with rhodamine dye and a UV lamp. Of the two commercial enzymes evaluated, the best treatment condition used Lipase 30 G (Specialty Enzymes & Biotechnologies Co®, Chino, CA, USA) at a concentration of 0.44 g/L, which decreased 35.59% of stickies. SebOil DG (Specialty Enzymes & Biotechnologies®) showed a stickies reduction of 21.5% when used at a concentration of 0.33 g/L. Stickies in kraft paper processes were actively controlled by the action of lipases, and future research should focus on how this enzyme recognizes its substrate and should apply synthetic biology to improve lipase specificity.